Atrial fibrillation is a common disorder and an important risk factor for stroke. Evidence from controlled clinical trials shows that adjusted-dose warfarin decreases the risk of stroke by two-thirds. Clinical practice guidelines recommend that most atrial fibrillation patients receive life-long anticoagulation; only about one-third of atrial fibrillation patients receive it. This study is a randomized controlled trial of an intervention (the RBC) to increase the appropriate use of anti-thrombotic therapy (warfarin and aspirin) for stroke prevention in patients with chronic atrial fibrillation. The intervention is a tailored patient-specific risk-benefit consult (RBC) that incorporates the risks and benefits of anti-thrombotic therapy for stroke prevention using the American College of Chest Physicians guidelines and the Outpatient Bleeding Risk Index, a validated risk assessment for major bleeding. The intervention is aimed at primary care providers practicing in different clinical settings. Evidence-based specific recommendations about the use of anti-thrombotic therapy, as well as the quality of anti-thrombotic management will be formulated for each atrial fibrillation patient in the intervention physician's panel. The control and the intervention physicians will also receive performance feedback in the form of an Achievable Benchmark of Care (ABC) that informs them of the percentage of their patient panel with atrial fibrillation that is receiving anti-thrombotic therapy in relation to the other physicians (intervention or control) in their group. The primary outcome is the change, pre-to post-intervention, in the proportion of eligible patients with chronic atrial fibrillation who are prescribed anti-thrombotics. This will be measured by the proportion of the eligible patients in each physician's panel for whom anti-thrombotics are currently prescribed at baseline, 6-months, and 12-months. Secondary safety outcomes are the proportion of individuals in the physician's panel with stroke, the proportion of anticoagulated patients with major bleeds, and the proportion of total treatment time during which the International Normalized Ratio is below, above and within therapeutic range. This study will test a novel and generalizable approach to increasing the appropriate use of anti-thrombotic therapy in patients with atrial fibrillation in a community setting and the findings will provide valuable insight into stroke prevention.